An automobile body is formed by joining a plurality of panel materials to each other by spot welding. In carrying out the spot welding, it is necessary to position and clamp various kinds of panel materials, which constitute the automobile body. Therefore, in order to position and clamp these panel materials, a plurality of positioning and clamping apparatuses are attached to a welding stage located in an automobile production line. Also, by mounting the positioning and clamping apparatus on a tip of a robot arm and operating and moving the robot arm, the positioning and clamping apparatus positions and clamps the panel materials. Further, on a carrier truck for carrying the panel materials, a plurality of positioning and clamping apparatuses are mounted for clamping the panel materials.
In any cases, the conventional positioning and clamping apparatus has the locating pin which is fitted to a positioning hole formed in the panel material that is a workpiece. By fitting the locating pin to the positioning hole, the panel material is positioned. Furthermore, in order to clamp the panel material, a clamp arm is incorporated into a slit formed in the locating pin so that the clamp arm can come out from the slit in clamping the panel material. This type of positioning and clamping apparatus is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2000-176874 (Patent Document 1) and Japanese Patent Application Laid-Open Publication No. 2003-260626 (Patent Document 2).